docs: def serialize(self, resources):
          """Serialize resource(s) according to json-api spec."""
          serialized = {
              'meta': {
                  'sqlalchemy_jsonapi_version': '4.0.9'
              },
              'jsonapi': {
                  'version': '1.0'
              }
          }
          # Determine multiple resources by checking for SQLAlchemy query count.
          if hasattr(resources, 'count'):
              serialized['data'] = []
              for resource in resources:
                  serialized['data'].append(
                      self._render_resource(resource))
          else:
              serialized['data'] = self._render_resource(resources)
  
          return serialized